Field
Exemplary embodiments relate to a touch screen panel and a method of manufacturing the same. More particularly, exemplary embodiments relate to a touch screen panel with improved wiring reliability, and a method of manufacturing the same.
Discussion
A touch screen panel is an input device allowing content displayed via a screen of a display device, or the like, to be selected (or otherwise interacted with) using an input device, such as a finger or hand of a user or an object, e.g., a stylus, etc. In this manner, the user may issue commands via touch or near touch interactions. To this end, such touch screen panels may be utilized to replace other input devices typically connected to a display device, such as a keyboard, a mouse, a trackpad, etc.
Conventional touch screen panels may be categorized based on touch detection schemes, such as, for example, a resistive scheme, a photo-sensing scheme, and a capacitive scheme. The capacitive scheme may be further classified into a self-capacitance scheme and a mutual capacitance scheme. The self-capacitance scheme may facilitate hovering (or near-touch) interactions, as well as multi-touch interactions. A typical self-capacitance type touch screen panel may include a plurality of conductive sensing electrodes spaced apart from one another and formed on a first surface of a substrate. In this manner, each of the plurality of conductive sensing electrodes may correspond to unique position information. Accordingly, when a user's hand or other touch object comes into contact (or near-contact) with the self-capacitance type touch screen panel, a change in capacitance associated with the conductive sensing electrodes may be detected, which may be further utilized to determine a position of interaction. In addition, conventional self-capacitance type touch screen panels may include a plurality of electrode wirings respectively connected to the plurality of conductive sensing electrodes. The plurality of electrode wirings may be arranged between adjacent conductive sensing electrodes.
Typically, the conductive sensing electrodes are formed by applying a hybrid film of a conductive material (e.g., a silver nanowire (AgNW) material) or a conductive transparent oxide (e.g., indium tin oxide (ITO)). To this end, a pad part and a wiring part, such as fan-out part, of the electrode wirings may include copper (Cu) at least because of its selectivity with AgNW and ITO and other processing characteristics. After metal wirings and bridges are formed with a metal, such as copper (Cu), a passivation layer is typically formed on the metal wirings and/or bridges to prevent (or at least reduce) corrosion. For instance, the pad part and the fan-out part may include an inorganic passivation film (e.g., SixNy) for passivation. Further, zinc indium oxide (ZIO) may be applied as a capping layer of the pad part.
It is noted, however, that the inorganic passivation layer and the capping layer are usually deposited at relatively low temperatures when plastic substrates are utilized with the touch screen panels. As such, the inorganic passivation layer and the capping layer may not be suitable in relatively high temperature conditions. Also, corrosion of the Cu in the pad part and the fan-out part may still occur. Moreover, because ZIO and SixNy have increasing moisture permeability as tissue density is lowered with lower deposition temperatures, the thickness of the capping layer and the passivation layer may be increased to improve their protective features. It is noted, however, that increasing thickness may increase stress, which may cause, at least in part, cracks to form in a lower substrate or hamper bending characteristics of such touch screen panels. Therefore, there is a need for an approach that provides efficient, cost effective techniques to improve the protection and passivation structures in touch screen panels.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.